The present invention relates generally to multiple access radio telephones and more specifically to a multiple access radio telephone system which provides concentration by switching remote subscriber stations to a smaller number of two-way radio channels and provides deconcentration by switching the radio channels to subscriber line terminals of a telecommunication switching system which correspond to the remote stations.
As illustrated in FIG. 3, a prior art multiple access radio telephone system comprises a line concentrator 60 which is formed by a switching matrix 61 having two pairs of terminals for connection to transceivers 71 and 72 and ten pairs of terminals for connection through hybrid transformers 8-1 through 8-10 to line terminals L.sub.1 through L.sub.10 of a telephone switching system 90. Transceivers 71 and 72 establish two-way radio channels to a group of remote subscriber stations 100 which are in one-to-one correspondence with line terminals L.sub.1 through L.sub.10 of the switching system 90. The transceivers 71 and 72 share a common antenna to establish two-way radio channels on frequecies f.sub.1, F.sub.1, f.sub.2 and F.sub.2 with remote subscriber stations 100-1 through 100-10. A controller 62 controls the switching matrix 61 in such a manner that the remote stations are concentrated to a smaller number of radio channels and deconcentrated to the corresponding subscriber line terminals as viewed from the remote stations to the switching system. Calls between the remote stations and subscriber stations external to the remote station group, or "extragroup calls" involve one two-way radio channel and a switched incoming or outgoing connection by the telephone switching system through one of the transceivers 71 and 72. However, for calls to be established between any two of the remote stations, or "intragroup calls", a switched connection is established between transceivers 71 and 72 as marked by solid and dot lines through two radio channels. Thus, the prior art system prevents a third party from originating a call when an intragroup call is in progress.